The "BACKGROUND OF THE INVENTION" of U.S. patent application Ser. No. 513,452 filed Apr. 23, 1990, entitled "PLURAL-ORDER SIGMA-DELTA ANALOG-TO-DIGITAL CONVERTERS USING BOTH SINGLE-BIT AND MULTIPLE-BIT QUANTIZATION" and assigned to General Electric Company is incorporated herein by reference. T. C. Leslie and B. Singh in their article "An Improved Sigma-Delta Modulator Architecture" appearing on pages 372-375 of the May 1990 PROCEEDINGS OF IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS & SYSTEMS describe circuitry for replacing a plural-bit digital-to-analog converter (DAC) in the feedback loop of a second-order sigma-delta modulator with a single-bit DAC and some associated digital circuitry. Replacement of the plural-bit digital-to-analog converter (DAC) in the feedback loop of a first-order sigma-delta modulator in each of the sigma-delta ADCs described in U.S. patent application Ser. No. 513,452 with a single-bit DAC and some associated digital circuitry generates sigma-delta ADCs described herein.